1. Field of the Invention
The present invention relates generally to a damper control apparatus, and more specifically, to a damper control apparatus for a fume hood which is operable to synchronize the movement of the fume hood sash, and the damper, thereby ensuring that an appropriate amount of air is withdrawn from the fume hood.
2. Background of the Invention
Fume hoods have long been used in research laboratories and the like to protect laboratory personnel from assorted chemical and biological hazards which are attendant with the research environment. Although many different fume hood designs exist, a fume hood, generally speaking, includes a table-like structure having a flat working surface and which positioned within a rectangular-shaped enclosure. This rectangular enclosure is defined by a roof member; left and right side walls, a front wall; and an opposite back wall. The front wall of the enclosure is defined, in part, by an aperture, and a fume hood sash is movably borne by the enclosure and is operable for substantially vertical motion into occluding relation relative to the aperture. This fume hood sash is often manufactured of a thick, relatively heavy gauge transparent panel which may be located in a closed position, or alternatively, may be selectively located to occlude the aperture thereby providing any desired amount of access to the working environment provided by the fume hood.
Fume hoods perform a number of laudatory functions, however, their most important features are to provide a safe working environment for laboratory personnel and to protect others from the harmful effects of chemical splashes and spills or exposure to potentially pathogenic biological agents, and further to evacuate noxious vapors and gases or other malodorous agents from the immediate fume hood environment. In this regard, fume hoods have included several different means for selectively positioning the sash in various locations thus varying the size of the access opening or aperture to meet the demands of the research environment. For example, previous laboratory fume hoods have incorporated various weighted counterbalance assemblies to provide a means for controlling or otherwise maintaining the size of the access opening. Furthermore, several prior art fume hood assemblies have included drive assemblies for closing or opening the sash of the fume hood upon the demand of the operator.
While the prior art fume hood designs have operated with varying degrees of success, they have had numerous shortcomings which have detracted from their usefulness. For example, one of the most noteworthy shortcomings of the prior art assemblies has been the means employed to evacuate or withdraw fumes from the fume hood environment. In this regard, it should be understood that due to the wide variety of research activities which may be undertaken in a fume hood, manufacturers have produced fume hoods having relatively constant air flow rates. Thus, the air flow rate which is selected is normally the rate which is suitable when the fume hood sash is in the fully open position. As one might expect, the amount of electrical power required to drive an associated blower assembly which achieves this required air flow rate can be substantial if many fume hoods are operating substantially simultaneously.
Another shortcoming attendant with the prior art fume hood designs result from characteristics inherent in their individual construction inasmuch as the prior art fume hoods frequently have been manufactured in a fashion where air withdrawn from the fume hood environment must be made up or otherwise delivered back to the laboratory. Consequently, it may be occasionally uncomfortable to work in the vicinity of fume hoods having this design.
Still another deficiency common with respect to the prior art fume hoods is their inability to provide emergency exhaust capability in the event of experimental mishap or accident, such as might be the case in the event of explosion or fire.
Therefore, it has long been known that it would be desirable to have an improved fume hood which addresses many of the deficiencies attendant with the prior art devices and practices and which further provides a convenient and cost effective means for providing a safe research environment.